Conventionally, a variable valve mechanism 100 of Patent Literature 1 shown in FIG. 6 is known as a variable valve mechanism that controls the lift amount, the working angle, and the opening/closing timing of a valve according to the operating state of an internal combustion engine.
This variable valve mechanism 100 includes a camshaft 101 which is rotated by a crankshaft (not shown) of the internal combustion engine, and a valve-operating member 103 that opens and closes a valve 102. A drive cam 104 is fixed on the camshaft 101 so as to be turnable integrally with the camshaft 101. Moreover, a swing cam 106, which includes a cam surface 105 engaging with the valve-operating member 103, is supported on the camshaft 101 so as to be turnable relative to the camshaft 101.
A variable link 109 is swingably supported on a control shaft 107, which is parallel to the camshaft 101, through an eccentric cam 108. One end of the variable link 109 is connected to the drive cam 104 by a ring-shaped link 110, and the other end of the variable link 109 is connected to the swing cam 106 by a rod-shaped link 111. The variable valve mechanism 100 transmits the power of the drive cam 104 to the swing cam 106 through the three links 109, 110, 111, and changes the swing angle of the variable link 109 by the eccentric cam 108, thereby changing the lift amount and the working angle of the valve 102 according to the operating state of the internal combustion engine.